Through the discovery process, the families of Sandy Hook victims hope to gain access to internal documents and depose Remington employees. The families argue that although the guns themselves may not be unsafe, Bushmaster's and Remington's marketing strategy deliberately targets young men, some of whom are inclined to violence.

Adam Lanza, 20, used a Bushmaster AR-15 to kill 20 children and six educators at Sandy Hook Elementary School in Newtown, Connecticut, in December 2012.

The gun makers had filed a motion to stay discovery, pending the judge's ruling on whether to strike the case based on a federal statute, the Protection of Lawful Commerce in Arms Act. The law protects gun makers if one of their firearms is used in a crime.

"For almost a year and a half, the families have waited patiently," attorney Josh Koskoff, a representative for the families of Sandy Hook victims, told CNN. "They have waited and watched as the defendants tried every tactic to avoid having to disclose a single document or answer a single question under oath. Now, that wait is officially over."

Attempts to contact gun makers for a response have not been successful.

Lawyers for the gun manufacturers and the families will be in court June 20 for oral arguments about whether the case should proceed. The case is scheduled to go to trial in April 2018.